Stupidity: Why would Gabriel have an item as valuable as the Poison Pill dangling from his neck (and therefore susceptible to falling off or being snatched by Ethan) during the airplane sequence rather than have put it in a secure location like a closed pocket before takeoff?
Stupidity: It took Leroy and Charlie too long (16 seconds) to realise the real J. Daniel Atlas is in their apartment, and he's not a hologram. It would take a microsecond for an ordinary human. (We, the viewers, knew immediately.) (00:10:48)